摘要:

The oscillatory phenomena in natural confection of low-Prandtl-number fluids were studied numerically in a rectangular cavity with horizontal temperature gradient at Prandtl number Pr = 0.01, aspect ratio A = J, 2, or 4, and Rayleigh number Ra = 104, 10s, or 106. In the case of A = 1 a main strong round roll cell was formed at Ra = 104. However, at Ra = 105and 106, two secondary roll cells in the core of a main roll cell were formed and rotated around the center of the system. The flow was oscillating. In the case of A = 2, i.e., a taller regime, the shape of the main roll cell varied with time at and above Ra = 104, and then the secondary complicated weak roll cells were formed above and below the main roll cells. This resulted in oscillatory phenomena even at Ra = 104. In the case of A = 4, three main roll cells were formed. At Ra = 105, secondary roll cells were formed between the main roll cells and then oscillation of flow occurred.

ISSN:1040-7782    

DOI:10.1080/10407789608913849

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The unstructured grid finite volume method has been applied to predict the linear and nonlinear attenuation characteristics of the expansion chamber type silencer system. In order to achieve grid flexibility and a solution adaptation for geometrically complex flow regions associated with the actual silencers, the unstructured mesh algorithm in context with the node-centered finite volume method has been employed. The validation cases for the linear and nonlinear wave propagation characteristics include the acoustic field of the concentric expansion chamber and the axisymmetric blast flow field with the open end. Effects of the chamber geometry on the nonlinear wave propagation characteristics are discussed in detail.

ISSN:1040-7782    

DOI:10.1080/10407789608913850

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The temporal formation of the buoyancy-driven flow structures in a bottom heated, shallow, cylindrical fluid layer was numerically studied. The unsteady three-dimensional Navier-Stokes and energy equations were discretized by the power law scheme and solved by the fully implicit Marker-and-Cell method. Computations were carried out for the pressurized argon (Pr=0·69) and water (Pr=6·1) layers for various Rayleigh numbers and heating rates of the layer. In the pressurized argon layer at a slightly supercritical Rayleigh number with Raf;=1·05Raca steady straight roll pattern was formed when the heating rate was very slow (a=0·001) after a long transient stage. When the heating rate was raised to a=0·01, a very different structure tike U-rolls was formed at steady state. In the water layer with Raf=l·05Rac, a straight roll pattern was again formed, but at a equals;0·07. At Raf;=1·13Rac, curved rolls with the three foci at the sidewall were formed for a=0·01. A pattern in the form of U-rolls appears at a=0·01. Regular concentric circular rolls prevail at a=1·0. When the Rayleigh number is further raised to 1·23Rac, the resulting steady flow is dominated by incomplete circular rolls with open ends near θ=0°

ISSN:1040-7782    

DOI:10.1080/10407789608913851

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The transient buoyancy, thermocapillary, and buoyancy-thermocapillary convection in two superposed immiscible liquid layers in a finite cavity with side heating has been studied in the laminar regime by solving the complete two-dimensional Navier-Stokes and energy equations using the spline integration method. The development of the flow and temperature field as well as the velocity, interface vorticity, and heat transfer in both layers has been evaluated. Oscillatory behavior has been observed at high Rayleigh numbers and Marangoni numbers for moderate Prandtl numbers. The behavior of the heat transfer between the two layers through the interface separating them has been found to be particularly interesting, with large heat transfer rates occurring across the interface near the end walls at high Rayleigh numbers.

ISSN:1040-7782    

DOI:10.1080/10407789608913852

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A stmianafytic analysis of in-tube turbulent forced convection is performed whose special computational feature is the combination of the method of lines, the finite volume technique, and a radial coordinate transformation. First, a numerical solution of the momentum equation was obtained by a simple Runge-Kutta integration scheme. Second, the energy equation was reformulated into a system of ordinary differential equations of first order. Each equation in the system controls the temperature along a line in a mesh consisting of concentric lines. Reliable analytic solutions for the temperature distribution of fluids in the region of thermal development can be determined for combinations of Reynolds and Prandil numbers. Predicted results for the distributions of mean bulk temperature and local Nusselt numbers for air, water, and oils compare satisfactorily with the available experimental data.

ISSN:1040-7782    

DOI:10.1080/10407789608913853

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A study is made on the flow and heat transfer of a viscous fluid confined between two parallel disks. The disks are allowed to rotate with different time dependent angular velocities, and the upper disk is made to approach the lower one with a constant speed. Numerical solutions of the governing parabolic partial differential equations are obtained through a fourth-order accurate compact finite difference scheme. The normal forces and torques that the fluid exerts an the rotating surfaces art obtained at different nondimen-sional times for different values of the rate of squeezing and disk angular velocities. The temperature distribution and heat transfer are also investigated in the present analysis.

ISSN:1040-7782    

DOI:10.1080/10407789608913854

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor